A number of primary discrete emotions emerge over the first year of life. Little is known about the relation between facial signs of these affects and concomitant central nervous system processes. The research proposed in this application is designed to provide the first fundamental knowledge on this question. It is novel methodologically in combining the precision of detailed coding procedures for the measurement of facial affect with sophisticated techniques for the analysis of noninvasively recorded brain activity. Infants at 6 months and 12 months of age will be studied. The same affect eliciting conditions will be presented at each age. These include presentation of a sweet and sour taste, placement on the visual cliff and the mother smiling or frowning at her infant. Brain electrical activity from left and right sided leads in the frontal and parietal regions will be recorded. The research will focus on hemispheric asymmetry associated with the presence of different facial signs of discrete emotion. These findings will provide important new information on the relation between maturational changes in brain function and the emergence of different emotion systems over the first year of life.